It's as simple as taking a photograph - with the flash on and red light feature off. That's it.
Now, go test it out. It only takes a moment! Watch photographs of your children over time too for any changes. Ania used to take regular photos with red eye up until her cancer diagnosis October 2013.
Healthy example of Ania at about 18 months ( December 2011)
And now Ania (October 2013)